JP2004205289A - Image measuring machine - Google Patents

Abstract

An image measuring device capable of performing high-speed imaging is provided.
An image of an object to be measured is obtained by photoelectrically converting an image of the object to be measured W formed on an imaging surface, and measurement of the object to be measured W is performed based on the obtained image. An imaging system 20 for acquiring an image of an object to be measured, a moving mechanism 50 for moving the object to be measured relative to the imaging system 20 in order to position the imaging system 20 at a measurement position of the object to be measured, Autofocus means 40 and 30 for performing focusing control for focusing the W image on the imaging surface, and control means 30 for performing control relating to image measurement including control of the autofocus means 40 and 30 are provided. The control means 30 starts the movement from a certain position different from the target measurement position and causes the autofocus means 40, 30 to start focusing control until the movement reaches the target measurement position.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image measuring machine that images a device under test and measures the device based on the captured image.
[0002]
[Prior art]
With respect to the measured object, as a measuring instrument for measuring the shape of itself, the shape of a pattern provided on the measured object, etc. based on the image thereof, an image of the measured object is taken by an imaging device, and formed on an imaging surface. There is an image measuring machine that photoelectrically converts an image of the measured object to generate an image of the measured object and performs measurement on the measured object based on the image. In recent years, this type of measurement has a configuration in which an imaging device is moved from a certain position to a target position to perform imaging. There is a CNC (Computerized Numerical Control) image measuring device as an image measuring device that automates this measurement operation (see Non-Patent Document 1).
[0003]
In this type of CNC image measurement that has been conventionally proposed, an imaging system is moved to a target measurement position, an auto focus (AF) operation is performed at a measurement location, and an image is taken in a focused state. In general, for example, an edge detection process is performed.
[0004]
[Non-patent document 1]
Nikon Corporation product catalog (CNC image measurement system NEXIV series)
[0005]
[Problems to be solved by the invention]
In this type of measurement, it is expected that precise images of a large number of measurement points will need to be acquired as the pattern of the object to be measured becomes more precise. Moreover, it is desired to perform imaging for a large number of measurement points in the shortest possible time while performing the AF operation.
[0006]
An object of the present invention is to provide an image measuring device that can perform high-speed imaging.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 is:
An imaging unit configured to photoelectrically convert an image of the measured object formed on an imaging surface to obtain an image of the measured object;
Measuring means for measuring the object to be measured based on the image,
A moving unit that relatively moves the object to be measured with respect to the imaging unit, in order to position the imaging unit at a measurement position of the object to be measured,
Auto-focusing means for performing focusing control for focusing the image of the object on the imaging surface,
Control means for starting focusing control by the autofocus means during movement to the measurement position by the movement means;
It is characterized by having.
[0008]
The invention according to claim 2 is
The image measuring device according to claim 1,
The control means compares a difference between a position at which movement by the movement means is started and the measurement position with respect to a position in the optical axis direction of the imaging means, and when the difference between the positions is outside a predetermined range. Is characterized in that after the movement by the moving means is started, the focusing control by the autofocus means is started.
[0009]
The invention according to claim 3 is:
The image measuring device according to claim 2,
When the difference between the positions is within a predetermined range, the movement by the moving means is started while the focusing control by the autofocus means is being performed.
[0010]
The invention according to claim 4 is
In the image measuring device according to any one of claims 2 and 3,
The predetermined range is a range in which the autofocus unit can perform focusing control.
[0011]
The invention according to claim 5 is
The image measuring device according to claim 1,
The control means determines whether the focus position of the imaging means has entered a range in which the focus control by the autofocus control is possible during the movement to the measurement position by the movement means. The focus control is started.
[0012]
The invention according to claim 6 is
The image measuring device according to claim 5,
The control unit may determine whether the focus position of the imaging unit is within a range where focusing control by the autofocus control is possible, according to a distance between the measurement position and a current position.
[0013]
The invention according to claim 7 is
An imaging unit configured to photoelectrically convert an image of the measured object formed on an imaging surface to obtain an image of the measured object;
Measuring means for measuring the object to be measured based on the image,
A moving unit that relatively moves the object to be measured with respect to the imaging unit, in order to position the imaging unit at a measurement position of the object to be measured,
Auto-focusing means for performing focusing control for focusing the image of the object on the imaging surface,
The difference between the position at which the movement by the moving means is started and the measurement position in the optical axis direction of the imaging means is compared, and when the difference between the positions is within a predetermined range, the movement is determined. Control means for starting movement to the measurement position in a state where focusing control by the autofocus means is performed at a start position;
It is characterized by having.
[0014]
The invention according to claim 8 is
The image measuring device according to any one of claims 1 to 7,
The control unit monitors whether or not the autofocus unit is in a state where the focus control can be performed after the start of the focus control. The focus control is started when the camera is stopped and it is determined that the focus control can be performed.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. In an embodiment of the present invention described below, a laser is used as one of the components of the autofocus (AF) means, and the object surface of the workpiece (workpiece) W is continuously irradiated with the laser to constantly focus. An example will be described in which a mechanism is used for performing control for displacing the relative positional relationship between the imaging unit and the object to be measured in the Z-axis direction (the optical axis direction of the imaging unit) so as to match. Further, there is provided an apparatus capable of performing a displacement operation in the Z-axis direction even during an XY-axis driving operation (movement to a target measurement position). This operation is performed by the CNC performed according to a predetermined operation program. That is, images are sequentially and continuously taken at a plurality of measurement positions on the object to be measured to obtain an image relating to the object to be measured.
[0016]
In the present embodiment, the focus control (focusing control) is continuously operated by using the laser while moving between the measurement positions while continuously performing imaging at a plurality of measurement positions by the CNC. As a result, at the time when the target measurement position is reached, that is, at the time when the movement operation of the XY axes is completed, control is performed so as to be in focus (focused state). This makes it possible to reduce the time required for focusing out of the preparation time required for imaging at a plurality of measurement positions, as compared with the case where focusing control is performed after reaching the target position.
[0017]
The present embodiment focuses on the fact that there are often regions at the same level in the target measurement position and its surroundings, especially on the movement route. That is, as shown in FIGS. 3 and 4, which will be described later, even if there is a groove, a step, or the like in the moving path, it is often the same height level as the target position when approaching the target position. are doing. Therefore, in many cases, the focus control can be performed in the area at the same height level immediately before reaching the target position.
[0018]
On the other hand, when there is an area having a different height immediately before the target position, the focusing control may not be completed before reaching the target position. Even in this case, since the focusing control is performed subsequent to the arrival, the time can be expected to be shorter than when the focusing control is started again after the arrival.
[0019]
FIG. 1 shows an outline of a configuration of an image measuring device according to an embodiment of the present invention. The image measuring device 10 illustrated in FIG. 1 detects an in-focus state, an imaging system 20 including an illumination device 21, an imaging device 22, and an objective lens system 23, a control device 30 including a CPU 31, a memory 32, and a storage device 33. It has a focus detection device 40 and a moving mechanism 50 including an XY stage 51 and a Z-axis driving device 52.
[0020]
In the imaging system 20, the imaging device 22 has an imaging device such as a CCD. The imaging device 22 forms an image of the device under test W on the image plane using the objective lens system 23 and another lens system (not shown), and acquires an image of the device under test. At this time, the illumination device 21 can illuminate the object surface of the device under test W.
[0021]
As shown in FIG. 2, the focus detection device 40 includes a laser light source 42 such as a laser diode for irradiating the object surface of the device under test W and a knife edge mirror 43 for causing the laser light to enter the objective lens system 23. The laser light source 42 is driven while the laser light source 42 is driven, while the laser light source 42 is driven by splitting light receiving elements 44a and 44b including photodiodes and the like for receiving the return light from the object surface of the object to be measured via the objective lens system 23. A detection device 41 that receives the output signals of 44a and 44b, generates a focus adjustment signal corresponding to the light receiving position of the return light spot SP, and sends the signal to the control device 30. The focus detection device 40, together with a Z-axis drive device 52 described later and the control device 30, constitutes an autofocus means for performing focus control for focusing an image of the measured object on the imaging surface of the imaging device 22.
[0022]
The two-divided light receiving elements 44a and 44b are arranged in parallel with a boundary part interposed therebetween. When the object surface of the object to be measured is at the focal position Fo, the two-part light receiving elements 44a and 44b cause the return light spot SP of the laser beam to move at the boundary between the two-part light receiving elements 44a and 44b. 44b, and are arranged in a positional relationship of incidence so as to have an equal irradiation area. The detection device 41 receives output signals from the two-piece light receiving elements 44a and 44b, performs processing such as differential amplification, and acquires a focus adjustment signal for performing focus adjustment. That is, when the object surface of the object to be measured is at the focal position Fo of the objective lens system 23, as described above, the return light spot SP is evenly distributed to the two divided light receiving elements 44a and 44b. Becomes 0. On the other hand, when the object plane of the object to be measured is located at the position Fr farther than the focal point, the return light spot SP is distributed in a state where the irradiation area increases toward the two-divided light receiving element 44a, so that the focus adjustment signal is, for example, + Δz. Conversely, when the object surface of the object to be measured is located at the position Fn closer to the focal point, the return light spot SP is distributed in a state where the irradiation area increases toward the two-divided light receiving element 44b, and thus the focus adjustment signal is, , -Δz. The control device 30 instructs the Z-axis driving device to move in the Z-axis direction based on the focus adjustment signal, and stops the movement in the Z-axis direction when the focus adjustment signal becomes 0.
[0023]
When the return light spot SP is not incident on any of the two-divided light receiving elements 44a and 44b, the detection device 41 outputs a signal indicating that the return light spot is out of the effective range, that is, focus control. Is sent to the controller 30 indicating that the state is not possible. Note that this signal may be a signal indicating the opposite state. That is, when the return light spot SP is incident on one of the two-divided light receiving elements 44a and 44b, a signal indicating that the return light spot is within the effective range, that is, a state in which focus control is possible. A signal indicating the presence may be sent to the control device 30. The control device 30 determines the start, the continuation, and the stop of the focus control based on whether the signal indicating that the focus control is not available is valid or invalid.
[0024]
The XY stage 51 constituting the moving mechanism 50 has an XY driving mechanism (not shown). The device under test W is placed on the XY stage 51 and is moved relatively to the imaging system 20 in the XY directions. This movement is performed based on a movement command including designation of XY coordinates. The Z-axis driving device 52 changes the relative positional relationship between the objective lens system 23 of the imaging system 20 and the XY stage 51. That is, the device under test W is relatively moved with respect to the imaging system 20 in the Z-axis direction. In the present embodiment, the actual displacement is on the imaging system 20 side. Of course, it is not limited to this. The XY stage side may be displaced in the Z-axis direction. Here, the Z axis is the optical axis direction of the imaging system 20. The moving mechanism 50 moves the imaging system 20 together with the control device 30 to move the object W relative to the imaging system 20 in order to position the focal position at a target measurement position on the object. Configure means. There is one or more measurement positions for the measured object. When there are a plurality of moving units, the moving unit moves the imaging system 20 so that the focal position is sequentially located at each measurement position. That is, the focus position of the imaging system 20 is sequentially moved from a certain position (current measurement position) to a target measurement position (the next measurement position) for a plurality of measurement positions.
[0025]
The moving mechanism 50 can move in the Z-axis direction by the Z-axis driving device 52. In the present embodiment, the Z-axis driving device 52 is used to move in the Z-axis direction in accordance with the Z-coordinate of each measurement position of the object to be measured. Also used for movement.
[0026]
The control device 30 includes a CPU (central processing unit) 31, a memory 32, and a storage device 33. An input device 35, a monitor 36, and the like can be connected to the control device 30. The control device 30 constitutes a computer system including these external devices. The storage device 33 has a readable and writable nonvolatile storage medium, and stores various programs executed by the CPU 31 and data. Examples of the various programs include a program for autofocus control, a program for movement control, a program for imaging processing, a program for image processing, and the like. In addition, as a program unique to the present embodiment stored in the storage device 33, while moving from a certain position different from the target measurement position to the target measurement position, focus control (focus control) is continuously performed using a laser. There is a program that causes the control device to function as control means for performing control for operating the control device. Further, there is a program for controlling the sequential movement of a plurality of measurement positions.
[0027]
Next, the operation of the image measuring device according to the present embodiment will be described with reference to FIGS. Prior to the description, the correspondence between the focusing control and the movement control due to the difference in the object surface shape of the object to be measured will be described with reference to FIGS. Thereafter, the operation will be described.
[0028]
FIG. 3 shows a relationship between the movement control and the focusing control when the groove C exists on the object surface of the measured object. FIG. 4 shows the relationship between the movement control and the focusing control when the step B exists on the object surface of the object W to be measured.
[0029]
In these figures, a pull-in range R is shown as a state in which focusing control by the autofocus means is possible. That is, when the focal position of the objective lens system 23 is within the pull-in range R, focusing control is possible. In the focusing control, the state where the laser beam is irradiated on the object W and the return light spot SP (see FIG. 2) is incident on only one of the two-divided light receiving elements 44a and 44b is the focusing state. It corresponds to the upper limit and the lower limit of the focus controllable state. The pull-in range R corresponds to the displacement of the return light spot SP between the upper limit and the lower limit, and the Z-axis driving device 52 is driven to move the imaging system 20 with respect to the workpiece W in the Z-axis direction. It shows the range of relative displacement in the direction.
[0030]
When the lower limit RL of the pull-in range R is located below the object plane of the measured object W and the upper limit RU is located above the object plane, focusing control can be performed in that state. Focusing control can be performed on both the S1 surface and the S3 surface in FIG. On the other hand, on the S2 surface, which is the bottom surface of the groove C, since the lower limit RL is higher than the S2 surface, the return light spot SP is not detected by any of the two divided light receiving elements 44a and 44b, and the focusing control cannot be performed. It becomes. In the case of FIG. 4, focusing control cannot be performed on the S5 surface, as in the case of the S2 surface of FIG. On the other hand, on the S6 surface, as in the S1 surface and the S3 surface in FIG.
[0031]
In the present embodiment, as will be described later, focus control is performed only in a state where focus control is possible. If the focus control is not possible, the focus control is stopped. By doing so, it is possible to prevent a delay caused by the following operation with a large stroke in the Z-axis direction. For example, in the case of the groove C, if it follows the bottom position, a follow-up operation is required to return to the original height level again before the target position, which may cause a delay in the focus control. In addition, there is also a problem that when the vehicle is made to follow beyond the control range, the following direction is easily lost. Therefore, in the present embodiment, when the focus control is not possible, the focus control is stopped to avoid the above-described problem.
[0032]
Next, with reference to FIG. 5, an operation of the image measuring device according to the embodiment of the present invention, in particular, a movement and an autofocus operation will be described. FIG. 5 shows a processing flow of continuous focus control, that is, a CNC measurement operation of performing focusing control while moving from a certain position to a target measurement position and performing imaging at the target measurement position. This process is executed by the CPU 31 of the control device 30. As a premise, it is assumed that the coordinates of each measurement position to be measured for the DUT have already been obtained, and that data is stored in the storage device 33 in advance. Of course, a configuration in which the coordinates of each measurement value are received from another system via a network may be employed. In addition, a configuration may be employed in which input is performed by teaching for each measurement position and measurement procedure. Furthermore, it is possible to adopt a configuration in which a specific position among the target measurement positions is designated as a position to be focused. In this case, the position can be designated by teaching or by address.
[0033]
At a certain position (start position), the CPU 31 determines whether the target Z position at the target measurement position (movement destination) is outside the pull-in range (step 111). This determination is made by comparing the coordinates of the current position on the Z axis with the coordinates of the target measurement position on the Z axis. Here, for example, if the position is outside the retraction range as shown at a position P5 in FIG. 4, the CPU 31 causes the Z-axis driving device 52 to set the imaging system 20 to a height corresponding to the Z coordinate of the target measurement position. Is instructed to move (step 112). The Z-axis driving device 52 moves the imaging system 20 relative to the workpiece W in the Z-axis direction according to the instruction.
[0034]
Next, when the target measurement position is within the pull-in range, and after the movement in the Z-axis direction by the Z-axis driving device 52 described above is completed, the CPU 31 starts focusing control (step 113). That is, the CPU 31 instructs the focusing detection device 40 to start focusing. In response to this, the detection device 41 of the focus detection device 40 turns on the laser diode or opens a shutter (not shown) to set the measurement position of the measured object, that is, the position to be focused. Then, the laser light is irradiated through the objective lens system 23. The return light is guided to the two-divided light receiving elements 44a and 44b via the objective lens system 23. If the return light spot is incident on either or both of the two-divided light receiving elements 44a and 44b, the signal is photoelectrically converted and output, and the detection device 41 performs arithmetic processing to obtain a focus adjustment signal. This signal is sent to the control device 30.
[0035]
The CPU 31 issues a command to the XY stage 51 of the moving mechanism 50 to move to a target position, that is, a target measurement position to be measured next (step 117). Further, in response to the movement command, the CPU 31 moves the workpiece W by displacing the XY stage 51 from the current position to the target measurement position. During this movement, the above-described focusing control is executed.
[0036]
Next, the CPU 31 checks whether the return light spot SP is out of the effective range, that is, whether the return light spot SP is in the pull-in range (step 119). More specifically, if the return light spot SP is incident on both and / or one of the two-divided light receiving elements 44a and 44b, it is within the effective range. is there. The signal is photoelectrically converted and output, and arithmetic processing is performed in the detection device 41 to obtain a focus adjustment signal. This signal is sent to the control device 30. The detection device 41 generates a signal indicating that the return light spot SP is out of the effective range based on the outputs of the two-piece light receiving elements 44a and 44b, and sends the signal to the control device 30.
[0037]
The CPU 31 determines whether the signal indicating that the return light spot SP is out of the valid range is valid or invalid based on the signal from the detection device 41 (step 119). When indicating that the returning light spot SP is out of the effective range, that is, when it is not in a state where the focusing control can be performed, the CPU 31 stops the focusing control. That is, the tracking operation of the Z axis is stopped (Step 120).
[0038]
On the other hand, when the return light spot SP is not out of the effective range, or when the Z-axis following operation is stopped, it is determined whether the focus control is possible (step 121). Here, when the return light spot is within the effective range, that is, when the focusing control is possible, the focusing control, that is, the Z-axis following operation is started (step 122).
[0039]
Next, it is determined whether the movement of the XY axes has reached the target position. If the movement has not reached the target measurement position, the processing from step 118 is repeated (step 123).
[0040]
If the target position has been reached, processing for terminating the focusing control is performed (step 124). That is, since the focusing control is being performed during the movement, it is confirmed here that the in-focus state has been reached, and the in-focus state is maintained. On the other hand, if the camera has not reached the in-focus state even after reaching the target measurement position as the target, focus is performed here and the in-focus state is maintained.
[0041]
In this state, imaging is performed by the imaging device 22, and the obtained image is loaded into the memory 32 (step 125). At the time of imaging, illumination is performed by the illumination device 21 as necessary.
[0042]
The CPU 31 processes the image fetched into the memory 32 based on the program (step 126). For example, an edge detection process is performed.
[0043]
As described above, the movement of the imaging system 20 is started from a certain position, focus control is performed during the movement, and imaging is performed at a target measurement position. This series of processing shows the procedure of the measurement processing for one measurement position. If there is a plurality of measurement positions on the object to be measured, when a series of processing is completed, the measurement position is referred to as a “certain position”, that is, a movement start position, and a measurement position serving as a target of the next measurement is set. As a target position, movement control and focusing control are performed by a similar series of procedures. If there is a measurement position at which focus control can be omitted, such as a case where measurement positions of the same level are consecutive among a plurality of measurement positions, a measurement position other than the measurement position to be measured first is used. For, it is possible not to perform focusing control. That is, the continuous focus control can be turned off.
[0044]
According to the present embodiment, since the focusing control is started while the imaging system 20 is moving, when the target measurement position is reached, the imaging device is in a focused state. Become. Further, when the return light is out of the effective range, that is, when the focusing control cannot be performed, the focusing control is stopped so that the deep tracking is not performed. Is preventing.
[0045]
Next, another embodiment of the present invention will be described with reference to FIG. The embodiment shown in FIG. 6 is different from the embodiment shown in FIG. 5 in that the focusing control is started at the same time as the movement is started, and after the movement of the imaging system is started from a certain position, the focusing is started when a specific area is reached. The focus control is started. Steps 113 to 115 in FIG. 6 are added between steps 111 and 112 and step 116 in FIG. Also, step 117 in FIG. 5 is changed to step 113 in FIG. Therefore, the other processing procedures are the same as those in FIG. Therefore, here, the added and changed processes will be mainly described, and the description of the same processes as those in FIG. 5 will be omitted.
[0046]
At a certain position (start position), the CPU 31 determines whether the target Z position at the target measurement position (movement destination) is outside the pull-in range (step 111). This determination is made by comparing the coordinates of the current position on the Z axis with the coordinates of the target measurement position on the Z axis. Here, for example, if the position is outside the retraction range as shown at a position P5 in FIG. 4, the CPU 31 causes the Z-axis driving device 52 to set the imaging system 20 to a height corresponding to the Z coordinate of the target measurement position. Is instructed to move (step 112). The Z-axis driving device 52 moves the imaging system 20 relative to the workpiece W in the Z-axis direction according to the instruction.
[0047]
Thereafter, the CPU 31 issues a command to the XY stage 51 of the moving mechanism 50 to move to the target position with the target measurement position to be measured next as the target position (step 113). Then, the CPU 31 acquires information indicating the current position accompanying the relative movement of the imaging system 20 from the XY stage 51, and monitors the current coordinate position (step 114). Then, it is determined whether or not the current coordinate position has reached a predetermined focus control start position (step 115). In this determination, when the distance between the target measurement position and the current position becomes equal to or less than a value corresponding to the predetermined focus control start position, it is determined that the focus control start position has been reached. As a result, the CPU 31 starts focusing control (step 116). The processing after step 118 is the same as that of the embodiment shown in FIG. 5 described above.
[0048]
According to the present embodiment, focus control is not performed until the imaging system approaches the target position. Therefore, useless focusing control can be suppressed. Other effects are as described above.
[0049]
The embodiment shown in FIG. 5 and the embodiment shown in FIG. 6 can coexist. For example, depending on the state of the object surface of the object to be measured, it is possible to select one of the measurement according to the processing procedure illustrated in FIG. 5 and the measurement according to the processing procedure illustrated in FIG. Good.
[0050]
Further, in the above-described embodiment shown in FIGS. 5 and 6, after performing the processing of steps 111 and 112, the movement control and the focusing control are performed. However, the present invention is not limited to this. Movement control and focus control may be performed without performing the processing of steps 111 and 112.
[0051]
In each of the above-described embodiments, the focus is detected by irradiating the laser beam and detecting the displacement of the return light. The present invention is not limited to this. Other methods may be used as long as focusing control can be performed while moving.
[0052]
【The invention's effect】
According to the present invention, imaging can be performed at high speed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an outline of a configuration of an image measuring device according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating an example of a configuration of an autofocus unit used in the image measuring device according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram illustrating a relationship between movement control and focusing control when a groove C is present on an object surface of an object to be measured.
FIG. 4 is an explanatory diagram showing a relationship between movement control and focusing control when a step B exists on the object surface of the device under test W;
FIG. 5 is a processing flowchart illustrating a continuous focus control, that is, a CNC measurement operation of performing focusing control while moving from a certain position to a target measurement position and performing imaging at the target measurement position.
FIG. 6 is a processing flowchart illustrating a continuous focus control, that is, a CNC measurement operation of performing focusing control while moving from a certain position to a target measurement position and performing imaging at the target measurement position.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Image measuring machine, 20 ... Imaging system, 21 ... Illumination device, 22 ... Imaging device, 23 ... Objective lens system, 30 ... Control device, 31 ... CPU, 32 ... Memory, 33 ... Storage device, 35 ... Input device, 36: monitor, 40: focus detection device, 41: detection device, 42: laser light source, 44a, 44b: two-piece light receiving element, 50: moving mechanism, 51: XY stage, 52: Z-axis drive device.

Claims (8)

An imaging unit configured to photoelectrically convert an image of the measured object formed on an imaging surface to obtain an image of the measured object;
Measuring means for measuring the object to be measured based on the image,
A moving unit that relatively moves the object to be measured with respect to the imaging unit, in order to position the imaging unit at a measurement position of the object to be measured,
Auto-focusing means for performing focusing control for focusing the image of the object on the imaging surface,
A control unit for starting focusing control by the auto-focusing unit while the moving unit is moving to the measurement position. The image measuring device according to claim 1,
The control means compares a difference between a position at which movement by the movement means is started and the measurement position with respect to a position in the optical axis direction of the imaging means, and when the difference between the positions is outside a predetermined range. The image measuring apparatus according to claim 1, wherein after the movement by said moving means is started, focusing control by said autofocus means is started. The image measuring device according to claim 2,
When the difference between the positions is within a predetermined range, the movement by the moving unit is started while the focusing control by the autofocus unit is being performed. In the image measuring device according to any one of claims 2 and 3,
The image measuring device according to claim 1, wherein the predetermined range is a range in which the autofocus unit can perform focusing control. The image measuring device according to claim 1,
The control means determines whether the focus position of the imaging means has entered a range in which the focus control by the autofocus control is possible during the movement to the measurement position by the movement means. An image measuring machine for starting focusing control. The image measuring device according to claim 5,
The image measurement apparatus according to claim 1, wherein the control unit determines whether the focus position of the imaging unit is within a range where focus control by the autofocus control is possible, based on a distance between the measurement position and a current position. Machine. An imaging unit configured to photoelectrically convert an image of the measured object formed on an imaging surface to obtain an image of the measured object;
Measuring means for measuring the object to be measured based on the image,
A moving unit that relatively moves the object to be measured with respect to the imaging unit, in order to position the imaging unit at a measurement position of the object to be measured,
Auto-focusing means for performing focusing control for focusing the image of the object on the imaging surface,
The difference between the position at which the movement by the moving means is started and the measurement position in the optical axis direction of the imaging means is compared, and when the difference between the positions is within a predetermined range, the movement is determined. Control means for starting movement to the measurement position in a state where the focus control by the autofocus means is performed at the start position. The image measuring device according to any one of claims 1 to 7,
The control unit monitors whether or not the autofocus unit is in a state where the focus control can be performed after the start of the focus control. An image measuring apparatus characterized in that when stopped and when it is determined that focus control is possible, focus control is started.

Images